Furnace



4 Ill w II June 18, 1929. ox 1,717,657

FURNACE Filed Sept. 2, 1926 im we INVENTOE! H TOE/V5;

Patented June 18, 1929.

UNITED STATES 1 1,717,657 P TENT 0FFICE,.'

-LEONARD BOX, or EAST sr. LOUIS, rumors;

FURNACE.

Application filedSeptember 2, 192a Serial' No. 133,143.

My invention relates to furnaces and especially to that type of furnace known in the trade as downdraft furnaces.

The primary object of my invention is'the production. of a furnace which, under all conditions, will approach approximately complete combustion of the fuel, thereby re sulting in greater economy and preventing the emission of smoke into the'open air.

Another object of my invent-ion'is the production of a furnace of maximum simplicity and one that may be constructed ata minimum cost.

Other and further objects and advantages of my invention will be apparent from the specification, claim and drawings, in which 2- Fig. 1 is a vertical cross-section.

Fig. 2 is a horizontal section, partly broken away. I

It is well known that but a very small percentage of the heat content of fuel is utilized, especially in domestic appliances. To reduce this waste and produce a more efficient furnace for domestic heating plants is the primary object of my invention.

The loss due to discharging smoke into the open air is well known. It is, also, well known that the ordinary furnace which admits air through the bottom of the grate and discharges it directly over the burning fuel results in the greatest waste. Therefore, many attempts have been made to confine the burning gases within the furnace and only emit the burnt products of combustion.

These attempts have resulted in what is known as down-draft furnaces, all of which, so far as the applicant is aware, are so designed that the air is admitted to the fire pot through a central tube of a fixed length, which discharges its air very close to the burning coal and which must necessarily be'restricted in size so that the velocity of the air is relatively high and the time it takes it to reach the burning coal very short so that it is relatively cold.

I have found by experience that the solution of this problem requires a large volume of air flowing in at a relatively low velocity and heated to the highest possible temperature.

To bring about this ideal condition, my invention consists of a hollow base 1, of the conventional type, provided with a grate 2 of any suitable design. A detachable annular fire bowl 3 is provided circumferentially with a series of ports 4, disposed peripherally about the base of the fire bowl 3. The ports fare in open communication with a smoke chamber 5, circumferentially disposedabout the fire bowl 3, and of relatively large capacity. I

Integral with the smoke chamber 5 is a circumferentially disposed air chamber 6, separated from the smoke chamber 5 by a partitionwall 7. Detachably superimposed upon the fire pot 3 is an annular wall8,which serves the purpose of increasingthe vertical height of thechamber 6. A gas dome 10 is provided adapted to rest on top of the partition wall 7 and. encloses the upper portion of the fire bowl 3 and the annular wall 8.

The lower portion 11 of thegas dome 10 immediately above the wall 8 is slopeddown wardly and inwardly to provide a passage 12 for the inflow of the heated air into the fire bowl.

The flue 13 is always in open communication with the smoke chamber 5, and may be intermittently put in open communication with the dome 10 by means of the damper 14. An air port 15, of ample capacity, puts the air chamber 6 in open communication with the air by means of the door 16, which is provided with a suitable register, not shown.

The fuel door 17 is adapted to be closed practically air-tight.

The flue 13 is provided with a vertically disposed partition wall 18, the lower end of said wall terminating at 19, and the upper end extending laterally into the dome at 20, thus dividing the flue into two compartments 21 and 22, the upper ends of the compartments being in intermittent communication with the space enclosed by the dome 10, and regulated by dampers 14 and 1 1 The lower ends of the compartments are always in open communication with the smokechamber 5.

On starting the fire the air port 15 is closed airtight by the door 16, and the ash pit door 23 is opened, permitting the air to flow in through the ash pit 24 and through the grate bars into the fire bowl 3 and up through the dome 10 directly into the flue 13, the damper and completely unites with the gases generated by the fuel, resulting in practically complete combustion of all the fuel. The hydrogen of the air and the carbon monoxide and water vapor pass downward through the ports 4 to the, fire bowl, into the smoke chamber and up the flue and out through the smoke. stack 26. p

It is obvious that the prerequisites for-complete combustion, viz a suflicient volume of highly heated air "brought into immediate contact with the gases generated by the fuel, arepresent thereby producing a furnace of maximum efiiciency at a minimum cost.

It will be noted that the airchamber is located so that the air absorbs heat from the walls of both the :fire bowl and the smoke chamber, thereby recovering heat that would otherwise be l0st, and the great efliciency of my furnace is largely due to the fact not only that a larger volume of air is heated, but that the air chamber is interposed between two highly heated chambers andthe temperature of the air is thus uniformly maintained at a 7 very much higherdegree.

an annular air chamber interposedbetween" said fire bowl and said annular smoke and gas chamber, means for admitting atmospheric air into said annular air chamber, means for discharging air from said air chamber into said fire bowl about the periphery of the upper portion thereof, means for directing inwardly and downwardly the air so admitted intofsaid firebowl from said air chamber, and means for regulating'and controlling the flow of air into said chambers and said furnace.

LEONARD BOX. 

